Java Tutorial/2D Graphics/Gradient Paint

Acyclic Gradient Paint

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import javax.swing.JComponent;
import javax.swing.JFrame;
class GradientPane extends JComponent {
  public void paint(Graphics g) {
    Graphics2D g2D = (Graphics2D) g;
    Point2D.Float p1 = new Point2D.Float(150.f, 75.f); // Gradient line start
    Point2D.Float p2 = new Point2D.Float(250.f, 75.f); // Gradient line end
    float width = 300;
    float height = 50;
    Rectangle2D.Float rect1 = new Rectangle2D.Float(p1.x - 100, p1.y - 25, width, height);
    GradientPaint g2 = new GradientPaint(p1, Color.WHITE, p2, Color.DARK_GRAY, false); // Acyclic
                                                                                        // gradient
    rect1.setRect(p1.x - 100, p1.y - 25, width, height);
    g2D.setPaint(g2); // Gradient color fill
    g2D.fill(rect1); // Fill the rectangle
    g2D.setPaint(Color.BLACK); // Outline in black
    g2D.draw(rect1); // Fill the rectangle
    g2D.draw(new Line2D.Float(p1, p2));
  }
}
public class AcyclicGradientPaint {
  public static void main(String[] a) {
    JFrame window = new JFrame("Acyclic Gradient Paint");
    window.setBounds(30, 30, 300, 300);
    window.getContentPane().add(new GradientPane());
    window.setVisible(true);
  }
}

A non-cyclic gradient

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.JComponent;
import javax.swing.JFrame;
public class BasicDraw {
  public static void main(String[] args) {
    new BasicDraw();
  }
  BasicDraw() {
    JFrame frame = new JFrame();
    frame.add(new MyComponent());
    frame.setSize(300, 300);
    frame.setVisible(true);
  }
}
class MyComponent extends JComponent {
  public void paint(Graphics g) {
    Graphics2D g2d = (Graphics2D) g;
    Color startColor = Color.red;
    Color endColor = Color.blue;
    int startX = 10, startY = 20, endX = 30, endY = 40;
    
    GradientPaint gradient = new GradientPaint(startX, startY, startColor, endX, endY, endColor);
    g2d.setPaint(gradient);
    g2d.draw(new Rectangle(20,20,200,200));
  }
}

Control the direction of Gradients

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class GradientsDirection extends JPanel {
  public void paint(Graphics g) {
    super.paint(g);
    Graphics2D g2d = (Graphics2D) g;
    GradientPaint gp1 = new GradientPaint(5, 25, Color.yellow, 20, 2, Color.black, true);
    g2d.setPaint(gp1);
    g2d.fillRect(20, 80, 300, 40);
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame("GradientsDirection");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new GradientsDirection());
    frame.setSize(350, 350);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }
}

Cyclic Gradient Paint

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import javax.swing.JComponent;
import javax.swing.JFrame;
class GradientPane extends JComponent {
  public void paint(Graphics g) {
    Graphics2D g2D = (Graphics2D) g;
    Point2D.Float p1 = new Point2D.Float(150.f, 75.f); // Gradient line start
    Point2D.Float p2 = new Point2D.Float(250.f, 75.f); // Gradient line end
    float width = 300;
    float height = 50;
    GradientPaint g1 = new GradientPaint(p1, Color.WHITE, p2, Color.DARK_GRAY, true); // Cyclic
                                                                                      // gradient
    Rectangle2D.Float rect1 = new Rectangle2D.Float(p1.x - 100, p1.y - 25, width, height);
    g2D.setPaint(g1); // Gradient color fill
    g2D.fill(rect1); // Fill the rectangle
    g2D.setPaint(Color.BLACK); // Outline in black
    g2D.draw(rect1); // Fill the rectangle
    g2D.draw(new Line2D.Float(p1, p2));
  }
}
public class CyclicGradientPaint {
  public static void main(String[] a) {
    JFrame window = new JFrame("Cyclic Gradient Paint");
    window.setBounds(30, 30, 300, 300);
    window.getContentPane().add(new GradientPane());
    window.setVisible(true);
  }
}

Drawing with a Gradient Color

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.JComponent;
import javax.swing.JFrame;
public class BasicDraw {
  public static void main(String[] args) {
    new BasicDraw();
  }
  BasicDraw() {
    JFrame frame = new JFrame();
    frame.add(new MyComponent());
    frame.setSize(300, 300);
    frame.setVisible(true);
  }
}
class MyComponent extends JComponent {
  public void paint(Graphics g) {
    Graphics2D g2d = (Graphics2D) g;
    Color startColor = Color.red;
    Color endColor = Color.blue;
    int startX = 10, startY = 20, endX = 30, endY = 40;
    
    GradientPaint gradient = new GradientPaint(startX, startY, startColor, endX, endY, endColor);
    g2d.setPaint(gradient);
    g2d.draw(new Rectangle(20,20,200,200));
  }
}

Gradients: a smooth blending of shades from light to dark or from one color to another

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class GradientsRedYellow extends JPanel {
  public void paint(Graphics g) {
    super.paint(g);
    Graphics2D g2d = (Graphics2D) g;
    GradientPaint gp1 = new GradientPaint(5, 5, Color.red, 20, 20, Color.yellow, true);
    g2d.setPaint(gp1);
    g2d.fillRect(20, 20, 300, 40);
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame("GradientsRedYellow");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new GradientsRedYellow());
    frame.setSize(350, 350);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }
}

Gradients in the middle

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class GradientsMiddle extends JPanel {
  public void paint(Graphics g) {
    super.paint(g);
    Graphics2D g2d = (Graphics2D) g;
    GradientPaint gp1 = new GradientPaint(0, 0, Color.orange, 0, 20, Color.black, true);
    g2d.setPaint(gp1);
    g2d.fillRect(20, 260, 300, 40);
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame("GradientsMiddle");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new GradientsMiddle());
    frame.setSize(350, 350);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }
}

Horizontal Gradients

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class GradientsLine extends JPanel {
  public void paint(Graphics g) {
    super.paint(g);
    Graphics2D g2d = (Graphics2D) g;
    GradientPaint gp1 = new GradientPaint(5, 25, Color.green, 2, 2, Color.black, true);
    g2d.setPaint(gp1);
    g2d.fillRect(20, 140, 300, 40);
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame("GradientsLine");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new GradientsLine());
    frame.setSize(350, 350);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }
}

String gradient paint

import java.awt.Color;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class StringGraidentPaint extends JFrame {
  public StringGraidentPaint() {
    getContentPane().add(new DrawingCanvas());
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setSize(500, 500);
    setVisible(true);
  }
  public static void main(String arg[]) {
    new StringGraidentPaint();
  }
}
class DrawingCanvas extends JPanel {
  Font font = new Font("Dialog", Font.BOLD, 40);
  FontMetrics fontMetrics;
  
  DrawingCanvas() {
    setSize(300, 300);
    setBackground(Color.white);
    fontMetrics = getFontMetrics(font);
  }
  public void paint(Graphics g) {
    Graphics2D g2D = (Graphics2D) g;
    int w = getSize().width;
    int h = getSize().height;
    g2D.setFont(font);
    GradientPaint gp = new GradientPaint(
                            30.0f, 50.0f,
                            Color.blue,
                            fontMetrics.stringWidth("Hello!"),
                            fontMetrics.getHeight(),
                            Color.red);             
    g2D.setPaint(gp);
    g2D.drawString("Hello!", 20,200);                                                 

  }
}

Vertical Gradient Paint

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class GradientsVertical extends JPanel {
  public void paint(Graphics g) {
    super.paint(g);
    Graphics2D g2d = (Graphics2D) g;
    GradientPaint gp1 = new GradientPaint(25, 25, Color.blue, 15, 25, Color.black, true);
    g2d.setPaint(gp1);
    g2d.fillRect(20, 200, 300, 40);
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame("GradientsVertical");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new GradientsVertical());
    frame.setSize(350, 350);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }
}